1. Field of The Invention
The present invention relates to an electrical connector for electrically connecting a daughter board to a circuit board, and particularly to a card edge connector for providing the daughter board with multi-directional retention.
2. The Prior Art
Conventional card edge connectors for use with a computer system usually utilize a normal engaging force from each of a plurality of contacts thereof to retain a daughter board inserted into an elongated slot of an insulative housing of the connector. The slot defines a plurality passageways arranged in rows on opposite sides thereof to respectively receive said contacts therein. However, when the computer system is subject to an external vibration, the normal engaging force of the contacts is not capable of providing the daughter board received in the connector with reliable and sufficient retention, which may possible cause an electrical disengagement between the circuit board and the daughter board resulting in a signal transmission error within the computer system. Such card edge connectors are disclosed in U.S. Pat. Nos. 4,795,374, 4,826,441, 4,842,538, 4,846,729, 4,869,672 and 5,026,292.
Additionally, Taiwan Paten Application No. 82,206,344 discloses a pair of opposite retention bars respectively located adjacent to opposite ends of the elongated slot to retain an inserted daughter board. However, the force arm provided by each retention bar is too short to stably support the inserted daughter board. U.S. Pat. Nos. 4,832,619 and 4,990,097 further disclose a pair of opposite towers for use with a compact daughter board located close to opposite ends of the slot of the connector. Each tower defines a groove with two opposite sidewalls for receiving one of opposite lateral edges of the inserted daughter board, but the sidewalls lacks elasticity to sufficiently clamp daughter boards of different thickness therebetween. U.S. Pat. Nos. 4,973,270, 5,013,264, 5,211,571 and 5,242,312 disclose a pair of an elastic retention bar(s) is/are integrally formed adjacent to at least one tower in the connector to elastically clamp the inserted daughter board. However, to some connectors providing the integral retention bars with the insulative housing, the methods for manufacturing the same require the use of multi-molds in molding process which becomes overly complicated. Furthermore, some retention bars with excessive elasticity may result in an unreliable electrical engagement through an undesired vibration as mentioned above. The above mentioned conventional connectors generally lack a vertical retention mechanism with respect to the inserted daughter board to ensure that the daughter board is accurately oriented within the slot and electrically engaged with the contacts therein. Other types of card edge connectors for retention with the daughter board are disclosed in Taiwan Patent Application Nos. 82,206,344, 84,210,361 and 84,213,255, and U.S. Pat. Nos. 4,204,737, 4,349,273, 4,781,612, 4,804,334, 4,826,447, 4,850,891, 4,898,540 and 4,990,097.
Accordingly, to resolve the above disadvantages, an object of the present invention is to provide a card edge connector with a first vertical retention means and a second horizontal retention means for providing an inserted daughter board with sufficient, multi-directional retention.
Another object of the present invention is to provide a card edge connector with a horizontal retention means which includes a pair of spring arms located above a pair of rails and each supported by a corresponding stop wall thereby providing a pair of spring arms with proper elasticity to clamp the daughter board therebetween.
The present invention is submitted in accordance with an improvement to a co-pending patent application Ser. No. 08/774,913 filed on Dec. 27, 1996.